Did you check the coolant level?

 

Coolant level good. I checked this first as I've had to add fluid twice after the light came on the dash.

 

This sounds like a thermostat problem. Although the fail safe mode would be open all the time, it sounds like it sticks, and stays closed for too long, then given time stars to work. There are many previous posts on the problem and changing it out is not all that difficult (I did post instructions on another post, maybe a page back or so). There are other possible answers, like water pump and such, but usually some evidence like a leak, or noise would be accompanying that type of thing

 

Thanks John. If it happens in the next day or so, I'll check the hoses to see if the thermostat appears closed when the temp gauge spikes. I'll check your older post on the replacement procedure. Unfortunately, there in no Bentley Manual available for our X3, as far as I know.

 

Update

Two weeks with no overheating, then yesterday problem back. Within 2 miles, temp gauge rises to red shortly after fan comes on and cabin heat shuts off. This time I noticed top radiator hose hot, but bottom hose barely warm. I want to think this is a thermostat failure, but everything I read is that it fails in the OPEN position. I've also not heard of anyone having issues with the electric water pumps on these X3's. I have added small amounts of coolant in the past, once just a couple weeks before this problem started. Could air have entered the system through the expansion tank, and now be trapped in the engine? If so, what is the best way to purge. Thanks all.

'07 X3
6sp
86,000

 

The thermostat is DESIGNED to fail in the open position but that doesn't mean it will always fail that way. They can become stuck closed and that's what it sounds like to me. Every one I've ever replaced had been stuck closed. If it were air in the system I would think you couldn't have gone 2 weeks without a problem.

 

You need to determine

why you are having to add fluid. You have to have a leak somewhere.